On Mon, Nov 30, 2020 at 09:48:46AM -0500, Steven Rostedt wrote: > On Thu, 26 Nov 2020 13:26:13 -0500 > Steven Rostedt <rost...@goodmis.org> wrote: > > > On Thu, 26 Nov 2020 06:52:45 +0100 > > Greg KH <gre...@linuxfoundation.org> wrote: > > > > > On Tue, Nov 24, 2020 at 10:39:17PM +0000, J. Avila wrote: > > > > Hello, > > > > > > > > In the ftrace logs we've collected internally, we have found that there > > > > are > > > > situations where time seems to go backwards; this breaks userspace > > > > tools which > > > > expect time to always go forward in these logs. For example, in this > > > > snippet > > > > from a db845c running a 5.10-rc4 kernel[1] (thanks for getting us the > > > > trace, > > > > John!), we see: > > > > > > Does the patch at: > > > https://lore.kernel.org/r/20201125225654.1618966-1-minc...@kernel.org > > > > > > resolve this issue for you? > > > > > > > I think I found the bug. Can you apply this patch and let me know if it > > fixes the issue for you? > > > > -- Steve > > > > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > > index dc83b3fa9fe7..bccaf88d3706 100644 > > --- a/kernel/trace/ring_buffer.c > > +++ b/kernel/trace/ring_buffer.c > > @@ -3291,7 +3291,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu > > *cpu_buffer, > > /* Nothing came after this event between C and E */ > > info->delta = ts - info->after; > > (void)rb_time_cmpxchg(&cpu_buffer->write_stamp, > > - info->after, info->ts); > > + info->after, ts); > > info->ts = ts; > > } else { > > /* > > > > Can I get a Tested-by from someone on the Google team, so that I can send > this upstream? It already passed all my internal testing, but I want to > make sure this is the fix for the issue I reference in the change log. > > -- Steve > > -- > To unsubscribe from this group and stop receiving emails from it, send an > email to kernel-team+unsubscr...@android.com. > Hi Steve,
Thanks for the quick turnaround! Daniel and I have both tested your patch and verified it's working on our end. Feel free to include: Tested-by: Daniel Mentz <danielme...@google.com> Tested-by: Will McVicker <willmcvic...@google.com> --Will
